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Species belonging to the genus Ochlandra Thwaites, the reed bamboos, play a significant role in sustaining the ecology of forests and the livelihood of rural communities in the Western Ghats. Karyology of this predominantly endemic genus of the region is poorly understood. Of the ten species belonging to the genus, chromosomal information is known for only two species. We studied mitotic and/or meiotic chromosomes of eight species, using squash and smear techniques. We report chromosome number (2n) of six species for the first time and two additional 2n reports of a previously studied species, O. travancorica (Bedd.) Gamble. The species and their chromosome numbers are: O. keralensis M. Kumar, Remesh & Sequiera and O. spirostylis M. Kumar, K. K. Seethal. & Sequiera (2n = 48), O. ebracteata Raizada & Chatterji (2n = 64), O. beddomei Gamble and O. setigera Gamble (n = 36, 2n = 72), O. scriptoria (Dennst.) C. E. C. Fisch. (2n = 72), O. wightii (Munro) C. E. C. Fisch. (n = 36, 2n = 60, 72) and O. travancorica (n = 24, 2n = 48, 72, 96). The basic chromosome number of the genus is x = 12. The somatic chromosomes of all studied Ochlandra species are small in size, with a length ranging from 0.45 to 2.50 µm. The present study has provided new perceptions on speciation, evolution and taxonomy of the genus and indicates that the taxonomic muddle in O. travancorica is due to intraspecific genetic variability as evident by chromosomal numerical variation and polyploidy.

Ochlandra travancorica is one of the economically important endemic reed bamboos of the Western Ghats. They are indiscriminately harvested for commercial usage in paper, pulp, and traditional cottage industries. This has drastically affected its viable populations in the Western Ghats. SSR markers were employed for characterizing the selected natural population to assess genetic diversity and infer genetic structure in their natural distribution range. The marker analysis revealed existence of high genetic diversity in sampled populations of O. travancorica (He=0.834, I=2.092). Analysis of molecular variance (AMOVA) revealed that a large proportion of genetic variation (84 %) is confined within the populations and only 16 percent was observed between populations. The pattern of genetic admixture generated in STRUCTURE analysis revealed high level of substructuring of populations. This might be due to close proximities of populations and high amount of gene flow (Nm=l .456) among them. Genetically diverse populations as indicated by number of, private alleles, gene diversity, heterozygosity and polymorphic content in different geographical areas indicate the need for ex situ conservation and genetic improvement programmes. Periyar and Malayatoor populations with significant genetic admixtures can also be recommended for resource conservation of reed bamboo species. [ABSTRACT FROM AUTHOR]